KARNAK 670HS Silicone Roof Coating System Guide

A property-team guide to 670HS Karna-Sil Ultra, substrate-specific preparation, repairs, base coats, silicone application, inspection, and maintenance.

Roofing Contractors Association of Texas member

Commercial roofing guide 02/20/2026

Understanding a KARNAK silicone restoration scope

KARNAK 670HS Karna-Sil Ultra is a single-component, high-solids, moisture-cure silicone roof coating used within substrate-specific restoration systems. A successful project depends on the complete assembly: cleaning, repair products, primer or base coat where required, detailed interfaces, coating coverage, cure conditions, and inspection.

This guide helps commercial property teams identify the information needed before a KARNAK silicone system is quoted.

Decision guide

What KARNAK publishes for 670HS

KARNAK describes 670HS as a high-solids silicone coating with weather and water resistance. Its published uses include spray polyurethane foam, previously silicone-coated roofs, galvanized and painted metal, concrete, several single-ply membranes, smooth built-up roofing, and modified bitumen, with substrate-specific primer or base-coat requirements.

The product page also states that surfaces require positive drainage and identifies preparation and application limits that belong in the project specification.

Manufacturer reference: KARNAK 670HS Karna-Sil Ultra technical information.

Decision guide

Survey questions that determine candidacy

Confirm the roof material, age, weathering, previous coatings, leaks, moisture, drainage, repairs, adhesion, contamination, corrosion, fasteners, seams, penetrations, flashings, and deck or support condition. Areas that cannot remain sound and dry require a separate repair or replacement decision.

The survey should also record access, occupied areas, air intakes, equipment, work-hour limits, and the weather exposure that will control daily application.

Decision guide

KARNAK silicone system components

Wash and substrate preparation

Prepare the roof to the current cleaning and soundness requirements for the identified material.

Repair and sealant work

Correct cracks, laps, seams, fasteners, penetrations, flashings, and transitions with compatible materials.

Primer or base coat

Use the substrate-specific layer identified for adhesion, rust control, bleed blocking, or membrane preparation.

670HS silicone finish

Apply and inspect the coating to the specified coverage across both details and field areas.

Decision guide

Metal roof restoration details

Bare galvanized metal and painted metal do not share the same preparation route. Existing paint, oxidation, red rust, section loss, fasteners, end laps, side laps, gutters, ridges, penetrations, and perimeter conditions must be documented.

Panel replacement, fastener work, corrosion treatment, compatible sealants, and reinforced detail work should be completed before the field coating.

Decision guide

Single-ply, BUR, and modified-bitumen routes

KARNAK publishes different base-coat or primer options for TPO, PVC, Hypalon, EPDM, built-up roofing, and modified bitumen. Weathering periods, cleaning, adhesion, bleed control, and repair details vary by substrate.

The roof specification should identify the exact system rather than use a generic instruction to coat an existing flat roof.

Decision guide

Weather, application, and quality controls

Surface dryness, rain risk, temperature, humidity, wind, material storage, mixing, coverage, and cure conditions should be monitored throughout the work. Roof areas must remain protected until each day’s work is complete and weather-ready.

Measured material use, photographs, detail inspections, and punch-list records provide a stronger closeout than appearance alone.

Decision guide

Define scope boundaries in the proposal

The proposal should separate included repairs from allowances and exclusions, identify inaccessible or untested areas, and state how additional wet or unsound construction will be handled if discovered. It should also define protection, shutdowns, access, staging, and other trade responsibilities.

Current product data, system guidance, detail drawings, and written warranty requirements where applicable should be included in the submittal process.

Decision guide

Maintenance of a silicone-coated roof

Keep drainage paths clear and inspect seams, penetrations, curbs, perimeters, equipment interfaces, repairs, and traffic areas on a planned basis and after severe weather. New penetrations or equipment work should be coordinated with compatible silicone repair details.

Future recoating begins with condition assessment, cleaning, repairs, and adhesion verification—not simply adding another layer.

Frequently asked questions

KARNAK 670HS Silicone Roof Coating Systems FAQs

Can any commercial roof be coated?

No. The surface must be compatible and sound, with moisture and existing defects addressed before the proposed coating is applied.

Will coating repair holes or loose panels?

No. Damaged metal, failed connections and other defects need their own repairs before coating.

Can a new coating go over an old coating?

Only where the old finish is suitable to remain. Adhesion, contamination and compatibility checks help establish the preparation required.

Is silicone always better than acrylic?

No. Product choice depends on the substrate, exposure, application conditions and future maintenance. Compare the specified system for your roof.

Does ponding-water resistance mean drainage can be ignored?

No. A coating does not increase drain capacity or correct the roof's fall. Persistent standing water still needs investigation.

Why do two coating quotes differ so much?

Preparation, repairs, primer, detail reinforcement and finished thickness can vary substantially. Compare those items as well as roof area.

Can the coating be applied in any weather?

No. Roof temperature, surface moisture, rain and curing conditions must fall within the selected product's limits.

Will a reflective coating reduce our energy bills?

It may reduce solar heat absorbed by the roof. Actual building savings depend on insulation, climate, HVAC use and other conditions.

Is an extra 10 or 20 years guaranteed?

No general lifespan promise applies to every roof. Review the actual proposed work and the terms of any applicable written warranty.

What information is useful before a coating survey?

The address, known roof material, existing coating name and current defects. Old product records and photographs help if available.

Move from guidance to property information

Discuss the commercial roofing decision for your facility

Share the property address, known roof information, current concern, and available project documents so the next step can be defined around the building.

Discuss Your Project

UK refurbishment experience, a Texas office

Refurbishment specialists

Our business grew through roof and cladding refurbishment in the UK. That experience shapes the work we now offer from our Texas office.

Repair what can be retained

We investigate the roof problem and explain what can be repaired, restored or replaced, so you can decide how to invest in the building.

Roofing and cladding together

We can coordinate roof, insulation, wall panel and drainage work, including the connections where separate repairs can leave problems behind.

A plan for your working building

We agree access, work areas and protection with your site team, including any restrictions needed while the roof is opened.